Diode-pumped solid-state laser gain module

ABSTRACT

A laser gain device ( 10 ) holds a laser slab ( 60 ) which is pumped by pump energy from at least one diode array assembly ( 24 ). An angle at which pump energy from the diode array assembly ( 24 ) impinges the laser slab ( 60 ) is adjustable via angle adjustment means. The laser slab ( 60 ) is mounted between edge bars ( 62, 64 ) which have laser slab spacers ( 84 ) extending therethrough, allowing laser slabs ( 60 ) of different widths to be mounted within the laser gain device ( 10 ). One or more pump energy shields ( 88, 90 ) are used to control the amount of pump energy entering the laser slab ( 60 ), and cooling liquid conduits ( 100 ) are provided throughout components of the laser gain device ( 10 ), serving to conductively cool a heat shield ( 12 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to optical components andmore specifically relates to a diode-pumped laser gain module.

[0003] 2. Description of the Prior Art:

[0004] Laser gain devices employing laser slabs use sources of opticalenergy to pump laser slabs and produce an output laser beam. Outputbeams may be used in applications such as optical lithography formicrochip production.

[0005] While laser gain devices have achieved success and are widelyused, they have some shortcomings. For example, many laser gain devicesare sized for use with a certain type of laser slab having specificdimensions, and even laser slabs designed to have the same dimensionsmay have slight variations that impact their exact fit into a laserdevice. The choice of a different laser slab—or the replacement of aworn or damaged laser slab with a new laser slab—may requirereconstruction of several parts of a laser system to accommodate a laserslab of a different size.

[0006] Further, it is desirable to maximize the amount of input opticalenergy (for example, from one or more diode arrays) entering the optimumarea of a laser slab. Removal of a laser slab from a laser gain devicefor repair or replacement may change the alignment or the amount ofoptical energy entering the laser slab, thereby decreasing the overallefficiency of the system.

[0007] The considerations of proper direction of input energy andoptimization of the laser device to accommodate specific laser slabsizes impact the heat dissipation of the laser device. As changes aremade to the laser device for the purposes of fitting laser slabs andoptimizing light input into laser slabs, the efficiency of heat removalfrom the laser device may change.

[0008] There is a need for a laser gain module that allows foroptimization of the gain module for different laser slabs, control ofthe amount and angle of light entering a laser slab, and efficient heatdissipation from within the gain module.

SUMMARY OF THE INVENTION

[0009] These and other goals are achieved by embodiments of the presentinvention.

[0010] According to one embodiment of the present invention, a lasergain module comprises top and bottom edge bars contacting the laser slaband having variable spacers for accommodating different slab sizes.

[0011] According to another embodiment of the present invention, a lasergain module is provided with one or more adjustable diode array bracketsfor changing the distance between diode arrays and a laser slab and alsofor changing the angle of diode light as it enters a laser slab.

[0012] According to a further embodiment of the present invention,changeable light shields are provided within a laser gain module betweena window and a laser slab for allowing control of the amount andlocation of light entering a laser slab.

[0013] According to still another embodiment of the present invention, aconductively cooled heat shield is provided for allowing easy removal ofa heat shield device and efficient use of cooling fluid in a laser gainmodule.

[0014] The above summary of the present invention is not intended torepresent each embodiment or every aspect of the present invention. Thisis the purpose of the Figures and the detailed description whichfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The foregoing and other advantages of the invention will becomeapparent upon reading the following detailed description and uponreference to the drawings.

[0016]FIG. 1 is an isometric view of a laser gain module according toone embodiment of the present invention.

[0017]FIG. 2 is an exploded view of the laser gain module of FIG. 1.

[0018]FIG. 3 is an exploded view of the laser slab housing of FIG. 1.

[0019]FIG. 4 is a front view of the laser gain module of FIG. 1.

[0020]FIG. 5 is a cross-sectional view of the laser gain module of FIG.4 taken along the line 5-5.

[0021]FIG. 6 is a cross-sectional view of the laser gain module of FIG.4 taken along the line 6-6.

[0022]FIG. 7 is a cross-sectional view of the laser gain module of FIG.4 taken along the line 7-7.

[0023]FIG. 8 is an isometric view of a laser gain module according toanother embodiment of the present invention with outer portions removedfor visibility.

[0024]FIG. 9 is a front view of the laser gain module of FIG. 8 withouter portions removed for visibility.

[0025]FIG. 10 is a cross-sectional view of the laser gain module of FIG.9 taken along the line 10-10.

[0026]FIG. 11 is a side view of laser slab housing members according toone embodiment of the present invention.

[0027]FIG. 12 is a cross-sectional view of the laser slab and laser slabsupports of FIG. 11 taken along the line 12-12.

[0028]FIG. 13 is a cross-sectional view of the window assembly of FIG.11 taken along the line 13-13.

[0029] While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. Itshould be understood, however, that the invention is not intended to belimited to the particular forms disclosed. Rather, the invention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] Turning now to the drawings, FIG. 1 shows an isometric, externalview of a laser gain module 10 according to one embodiment of thepresent invention. The laser gain module 10 comprises a heat shield 12including a first heat shield component 14 and a second heat shieldcomponent 16. The structure and function of the heat shield 12 will beexplained more fully below. The laser gain module 10 contains asolid-state laser slab 60 (as shown in FIG. 3, below) which is opticallypumped by diode arrays, also provided within the laser gain module 10,in diode array assemblies 24. The diode array assemblies 24, in turn,are held by diode mounts 18, which support the diode array assemblies 24and also allow for translation of the diodes toward and away from thesolid-state laser slab 60 and for control over the angles at which lightleaving the diode array assemblies 24 enters the solid-state laser slab60. According to one embodiment, the control of translation and angle ofthe diode mounts 18 allows for control and optimization of pumpuniformity and optical path difference (OPD) uniformity.

[0031] The diode mount 18 b, shown in FIG. 1, is held on the laser gainmodule 10 along a lower mount portion by spring-loaded bolts 20 driveninto a gain module chassis 36. The spring-loaded bolts 20 are loadedwith compression springs 21 which exert an inward force on a lower leverportion 22 of the diode mount 18. The direction of the force exerted onthe lower lever portion 22 of the diode mount 18 by the compressionsprings 21 is shown by arrow “A” in FIG. 1. Leverage on the diode mount18, as described more completely below with respect to FIG. 5, moves thediode array assembly 24 outwardly, in the direction shown by arrow “B”in FIG. 1. The diode array assembly 24 is prevented from movingoutwardly by a diode angle adjustment screw 26 provided within anadjustment bracket 28, which in turn is mounted to a slab housing block80. The diode angle adjustment screw 26 presses against a diodeadjustment support 32 which protrudes upwardly from the diode arrayassembly 24 through a slot provided within the adjustment bracket 28.While the diode adjustment support 32 is shown as a screw extendingupwardly from the diode array assembly 24, the diode adjustment supportcould be other devices as well, such as a pin, dowel, or platformsecured to the diode array assembly 24 or otherwise adapted to move withthe diode array assembly 24.

[0032] The first and second heat shield components 14 and 16 are mountedto a liquid-cooled heat shield base 34 provided on a gain module chassis36. An output beam aperture 37 is provided within the heat shield 12 forallowing an output beam to exit when the laser slab 60 converts pumpenergy to the output beam.

[0033] Turning now to FIG. 2, the heat shield components 14 and 16 areshown elevated over the heat shield base 34 to which they are mounted.First and second diode mounts 18 a and 18 b attach to opposite sides ofthe gain module chassis 36, and the spring-loaded bolts 20 extendthrough apertures 38 provided within lever portions 22 of the diodemounts 18 a and 18 b. Outer mount shields 40 are mounted to the diodemounts 18 a and 18 b to contain the diode array assemblies 24 and toprotect the diode array assemblies 24 from damage. Adjustment brackets28 for facilitating adjustment of the diode angles relative to laserslab 60 are provided on the gain module chassis 36.

[0034] The gain module chassis 36 supports a slab housing 42 holding asolid-state laser slab 60 which is optically pumped by energy fromenergy emission regions 25 of the diodes within the diode arrayassemblies 24. The laser slab 60, the diode array assemblies 24, and thesurrounding support structure must be cooled due to the heat generatedby the optical pumping process and by the generation of an output beamwithin the laser slab 60. As will be described more completely below,cooling is accomplished using a liquid cooling system, using liquidconduits provided in system components.

[0035] Several features of the laser gain module 10 related to coolingare shown in FIG. 2, including a coolant entry 44, a coolant outlet 46,diode coolant conduit assemblies 48 (which include diode coolantconduits 50, O-rings 52, and diode coolant conduit brackets 54 and sealrings 56), and mount coolant ports 58. The diode coolant conduitassemblies 48 allow for the provisioning of coolant to the diode arrayassemblies 24 even as the diode array assemblies 24 are angled andtranslated with respect to the laser slab 60. The functions of thecooling-related components will be explained more completely below withrespect to FIGS. 5-10.

[0036]FIG. 3 is an exploded view of the slab housing 42. The slabhousing 42 serves to hold a solid-state laser slab 60, to direct coolantto and around the laser slab 60, and to provide windows through whichpump radiation is directed to the laser slab 60. The laser slab 60 issupported between first and second edge bars 62 and 64. According to oneembodiment, the slab 60 is held in place along edge bar interfaces 118(shown in FIG. 12). It is preferable to bond the slab to the edge bars62 and 64 using a thermally conductive and somewhat elastomericadhesive, such as boron-nitride filled siliconeroom-temperature-vulcanizing (RTV) adhesive. The present invention mayemploy slabs made of any type of solid-state laser slab material, forexample Nd:YAG. It is preferred to keep the laser slab 60 at a constanttemperature, even when the laser gain device is not in operation. Toprovide heating to the laser slab 60, the edge bars 62 and 64 areelectrically heated by current through first and second edge barconductors 66 and 68. The first and second edge bars 62 and 64 are heldtogether by edge bar brackets 70, which include coolant conduits todirect coolant from the chassis 36, positioned below the laser slab 60,through edge bar bracket apertures 72 into edge bar coolant apertures74, through the edge bars 62 and 64, and then back down into the chassis36. The edge bar bracket apertures 72 and the edge bar coolant apertures74 are sealed by O-rings 76 to prevent coolant leakage.

[0037] Each of the slab housing blocks 78 and 80 contains a window 86through which pump energy enters the laser slab 60. As described ingreater detail below, pump energy shields 88 and 90 may be positionedbetween one or both windows 86 and the laser slab 60 to control pumpenergy entering the laser slab 60.

[0038] The laser slab 60 is sealed to each of the slab housing blocks 78and 80 with slab seals 92. The slab seals 92 allow the laser slab 60 tobe liquid cooled. The slab seals 92 are preferably compressed betweenthe housing blocks 78 and 80 and the laser slab 60 and in one embodimentare comprised of compressible material such as Viton® material made byDuPont, or silicone rubber material. According to one embodiment, theslab seals 92 are compressed to a width of approximately 0.6 inch,though greater or lesser compressions may be used depending on thechoice of material. Any seal material compatible with the coolant may beused, and it is preferred to choose a material that experiences littleto no degradation when exposed to laser light from the diode arrayassemblies 24 or generated within the laser slab 60.

[0039] Also shown in FIG. 3 are mounting screws 94 for mounting the edgebar brackets 70 to the edge bars 62 and 64 and assembly pin nuts 96 forthe assembly pins 82 to screw into. In the embodiment shown in FIG. 3,the diode adjustment bracket 28 opposes and is connected to a topassembly pin 82.

[0040] Turning now to FIG. 4, a side view of a laser gain module 10according to the present invention is shown. In the side view of FIG. 4,the outer mount shield 40, has been removed to provide a more directview of the diode array assembly 24. Diode electrical connectors 98provide power to and allow control of pump radiation from the diodearray assemblies 24 shown.

[0041] Turning now to FIG. 5, a cross-section along the line 5-5 of FIG.4 is shown. This cross-sectional view more clearly shows theconstruction of the laser gain module 10 and illustrates the assembly ofseveral components of the laser device.

[0042] Cooling liquid conduits 100 are shown extending throughoutseveral components of the laser gain module 10, including the gainmodule chassis 36 and the diode mounts 18. Heat shield conduits 102extend through the heat shield base 34 and slab cooling conduits 104 areshown on opposing sides of the laser slab 60, positioned between thelaser slab 60 and the windows 86. The diode coolant conduits 50 fordirecting coolant liquid between the gain module chassis 36 and thediode mounts 18 are also shown, along with O-rings 52 and seal rings 56.The seal rings 56 ensure that coolant liquid does not leak when thediode mounts 18 are tilted or placed at different spacings within thelaser gain module 10.

[0043]FIG. 5 illustrates the ability to control the angle of pump energyentering the laser slab 60 as well as translation of the diode arrayassemblies 24 toward and away from the laser slab 60. The diode mounts18 a and 18 b in the embodiment shown in FIG. 5 are provided with diodetilt fulcrums 106. When the lower lever portions 22 of the diode mounts18 a and 18 b are biased inwardly toward the gain module chassis 36, inthe directions shown by the arrows “D” of FIG. 5, a force will beexerted away from the gain module chassis 36, in the directions shown bythe arrows “E” of FIG. 5, at the diode angle adjustment screws 26. Thatis, as the lower lever portion 22 of the first diode mount 18 a isbiased inwardly, toward the right in FIG. 5, the top lever portion 108of the first diode mount 18 a, which contains the diode array assembly24, is biased outwardly, toward the left. Similarly, the lower leverportion 22 of the second diode mount 18 b is biased inwardly, toward theleft, and the top lever portion 108 of the diode mount 18 b is biasedoutwardly, toward the right. This force results from lever actionpushing top lever portions 108 of the diode mounts 18 away from thelaser slab 60. The diode angle adjustment screws 26 oppose the diodeadjustment supports 32, which are moved toward and away from the centerof the gain module chassis 36 within adjustment support slots 110. Thus,by turning the diode angle adjustment screws 26 inwardly (toward thelaser slab 60), the angle of light emitted from the energy emissionregions 25 of the diode array assemblies 24 may be adjusted downwardly,and by turning the diode angle adjustment screws 26 outwardly, the angleof light emitted by the energy emission regions 25 of the diode arrayassemblies 24 may be adjusted upwardly.

[0044] The embodiment shown in FIG. 5 also allows for the distance fromeach of the diode array assemblies 24 to the laser slab 60 to be alteredby the placement of diode spacers between one or both of the diode tiltfulcrums 106 and the first and second slab housing blocks 78 and 80. Inone embodiment, the diode spacers are strips of stainless steel tapeallowing the spacing of one or both of the diode mounts 18 in incrementsof the tape thickness. According to one embodiment, stainless steel tapehaving a thickness of approximately 0.005 inch is used for diodespacing. Thus the diode array assemblies 24 may be translated toward oraway from the laser slab 60 via the diode spacers or angled with respectto the laser slab 60 via the adjustment screws 26 to assure that adesirable amount of pump radiation is inserted into the laser slab 60 atdesired angles. This assists in achieving a well-defined, homogeneouslyilluminated window for each side of the laser slab 60. Further, diodearray adjustment allows for the direction of pump radiation toward thelaser slab 60 so as to compensate for thermal non-uniformities in theslab. While FIG. 5 shows a two-sided laser gain module 10, it is to beunderstood that the principles of the present invention may, in analternative embodiment, be directed to a laser gain module in which alaser slab is pumped from only one side.

[0045] Turning now to FIG. 6, a cross-sectional view of a laser gainmodule 10 along the line 6-6 of FIG. 4 is shown. This cross-sectionalview further shows the cooling liquid conduits 100 extending through thelaser gain module 10. This view also shows an assembly pin 82 extendingthrough the first and second slab housing blocks 78 and 80 and alsoextending through a laser slab spacer 84, which keeps the slab housingblocks 78 and 80 spaced at an optimum distance for the laser slab 60. Inthe embodiment shown in FIG. 6, the laser slab spacer 84 isapproximately twice the width of the laser slab 60. The presentinvention contemplates laser slab spacers 84 having a range of widths,with specific widths chosen based on the width of the laser slab 60 andthe desired spacing of the slab housing blocks 78 and 80. Cooling liquidconduits 100 in the diode mounts 18 can also be seen in this view. Firstand second edge bars 62 and 64 are shown holding the laser slab 60 fromthe top and bottom, respectively.

[0046] According to one embodiment, the laser slab spacers 84 areapproximately the width of the laser slab 60 and they keep the first andsecond slab housing blocks 78 and 80 an appropriate distance from thelaser slab 60, preventing the slab housing blocks 78 and 80 fromcontacting the laser slab 60.

[0047] The use of changeable laser slab spacers 84 allows for theadjustment of spacing between the slab housing blocks 78 and 80 forparticular laser slabs, or for a single laser slab whose thicknesschanges over time. According to one embodiment, the laser slab spacers84 are made of stainless steel, but other materials such as ceramics,plastics, and other metals may be used. It is preferred to construct thelaser slab spacers 84 of materials that have thermal expansioncharacteristics similar to the thermal expansion characteristics of theassembly pins 82 to minimize thermal expansion problems.

[0048] Laser slab thicknesses may change as a result of polishing or ofwork done on the laser slab to remove flaws on the laser slab surface.When laser slabs 60 having different thicknesses are used in the lasergain module 10, the laser slab spacers 84 allow the re-use of remaininglaser gain module components, reducing or eliminating the need forremanufacturing or customization of other laser gain module components.The laser slab spacers 84 also allow for optimization of seals arounddifferently-sized laser slabs 60, preventing or reducing leaking ofcoolant from the area of a narrower slab and preventing or reducing theovercompression of seals surrounding larger slabs. Overcompression ofseals can lead to slab damage and damage to hardware surrounding theslab.

[0049]FIG. 7 shows a cross-sectional view of a laser gain module 10along the line 7-7 of FIG. 4. Cooling liquid conduits 100 in the firstand second slab housing blocks 78 and 80 transport cooling liquid to andfrom the heat shield base 34 (shown in FIG. 2) as explained more fullybelow. Cooling liquid conduits 100 can also be seen extending throughthe diode array assemblies 24. The first and second slab housing blocks78 and 80 are provided with slab cooling liquid diverters 112 fordiverting cooling liquid through the slab cooling conduits 104 andthereby to directly cool the laser slab 60. According to one embodiment,cooling liquid is diverted to the laser slab 60 at a ratio ofapproximately 8:1 in comparison to the diversion of cooling liquid tothe heat shield base 34. In this embodiment, for example, ifapproximately eight gallons per minute of cooling liquid are directed tothe slab cooling conduits 104 for cooling the laser slab 60, thenapproximately one gallon per minute of cooling liquid will be directedto the heat shield base 34. Greater or lesser diversion ratios may beused to achieve efficient cooling of the laser slab 60 and surroundingcomponents.

[0050] Turning now to FIG. 8, an isometric view of an assembled lasergain module 10 is shown with heat shield components 14 and 16, outermount shields 40, and diode mounts 18 removed to give a more completeexterior view of an assembled gain module. The window 86 within thesecond slab housing block 80 allows pump radiation from the diode arrayassemblies 24 (not shown in FIG. 8) to enter the laser slab 60(positioned behind the window 80 of FIG. 8). Edge bar conductors 66 and68 extend from the edge bars 62 and 64 (not shown in FIG. 8) into anedge bar current input 114 which allows for the heating of the edge bars62 and 64 and the maintenance of the edge bars 62 and 64 at a propertemperature.

[0051] Also visible in FIG. 8 are the coolant entry 44 and the coolantoutlet 46 of the gain module chassis 36. Cooling liquid conduits 100 areprovided within the gain module chassis 36, and table mounts 116 areprovided for mounting the gain module chassis 36 to a stable platform.

[0052] A front view of the laser gain module 10 with heat shieldcomponents 14 and 16, outer mount shields 40, and diode mounts 18removed is shown in FIG. 9, and a cross-sectional view along the line10-10 of the laser gain module 10 with these shields and diode arraymounts removed is shown in FIG. 10. Cooling liquid conduits 100 providedin the gain module chassis 36 carry cooling liquid upwardly to thecooling liquid conduits 100 within the slab housing blocks 78 and 80.Cooling liquid diverters 112 divert cooling liquid to the laser slab 60.O-rings 76 are provided at the interfaces of the gain module chassis 36and the slab housing blocks 78 and 80 and also at the interfaces of theheat shield base 34 and the slab housing blocks 78 and 80.

[0053] According to one embodiment of the present invention, coolantliquid is directed through the laser gain module 10 and used to cool aheat shield 12, as shown in FIGS. 1 and 2. The heat shield 12 serves tocontain non-lasing radiation within the laser gain module 10, absorbingnon-lasing radiation and protecting surrounding components from thenon-lasing radiation. Coolant liquid, such as purified water, enters thegain module chassis 36 through a coolant entry 44 and exits the gainmodule chassis 36 through a coolant outlet 46 as shown in FIG. 2.Coolant enters and exits the diode mount 18 b through a diode coolantconduit assembly 48, which includes diode coolant conduits 50 contactingthe gain module chassis 36 at O-rings 52. A diode coolant conduitbracket 54 supports the coolant conduits 50 and provides for spacingbetween the diode mount 18 b and the gain module chassis 36. The coolantconduits 50 are provided with seal rings 56 to prevent leakage ofcoolant from mount coolant ports 58 when the diode angles are adjustedas described above. The gain module chassis 36 includes cooling liquidconduits which direct coolant upwardly through the slab housing 42 andto the heat shield base 34. The coolant then flows downwardly throughthe slab housing 42 to the coolant outlet 46. As shown in FIGS. 3, 7,and 10, cooling liquid conduits 100 are provided within the slab housingblocks 78 and 80 to direct coolant upwardly to the heat shield base 34.Heat shield coolant conduits 102, as shown in FIGS. 5, 6, and 10 runthrough the heat shield base 34. Thus, as the heat shield components 14and 16 are heated by the absorption of non-lasing radiation, the heatshield base 34 conductively cools the heat shield components 14 and 16and keeps them at a safe operating temperature, thereby protecting thesurrounding environment from unwanted temperature increases. As shown inFIGS. 1 and 2, the heat shield 12 may be provided with angled or curvedportions to absorb stray radiation in the laser gain module 10.

[0054] A side view of the laser slab housing blocks 78 and 80 is shownin FIG. 11. An edge bar bracket 70 is shown for holding the edge bars 62and 64 (not shown in FIG. 1) between the slab housing blocks 78 and 80,and the edge bar conductors 66 and 68 extend behind the edge bar bracketand toward the edge bars 62 and 64. A cross-sectional view of theassembly along the line 12-12 is shown in FIG. 12.

[0055] In FIG. 12, the laser slab 60 is shown mounted between the firstand second edge bars 62 and 64 and held between edge bar slab interfaces118. Cooling liquid conduits 100 extend through the edge bar brackets 70and through the first and second edge bars 62 and 64. Laser slab spacers84 are also shown in FIG. 12, with one laser slab spacer 84 shown in thefirst edge bar 62 and two laser slab spacers 84 shown in the second edgebar 64.

[0056] Turning now to FIG. 13, a cross-sectional view along the line13-13 of FIG. 11 shows the window 86 with a surrounding slab seal 92.Upper and lower pump energy shields 88 and 90 are provided on the window86. While the embodiment of FIG. 13 shows both upper and lower pumpenergy shields 88 and 90, it is to be understood that only one of thetwo shields may be provided in some embodiments. The pump energy shields88 and 90 are provided to control the amount of pump energy entering thelaser slab 60, and the location of the laser slab 60 through which pumpenergy is input into the laser slab 60. To control the vertical locationon the laser slab 60 at which pump energy is allowed to enter the laserslab 60, upper pump energy shields 88 and lower pump energy shields 90are provided so that not all optical energy entering through the windows86 necessarily enters the laser slab 60. Thus, the pump energy shields88 and 90 define an aperture for controlling the amount and direction ofpump energy that enters the laser slab 60.

[0057] According to one embodiment, the pump energy shields 88 and 90are provided to keep optical pump energy within an ideal energy inputarea of the laser slab 60. For efficient and reliable laser operation,it is desirable to keep isotherms within the laser slab 60 runningvertically (in the direction of arrow C of FIGS. 3 and 12) through thelaser slab 60. One benefit of vertical isotherms is better uniformity ofthe refractive index throughout the laser slab 60. The laser slab 60 isheated to a greater temperature in locations excited by pump energy.Thus, if pump energy is concentrated toward the center of the laser slab60, the center of the laser slab 60 will heat up and the edges of thelaser slab 60 will stay at a relatively cooler temperature. Similarly,if pump energy is allowed to approach the edges of the laser slab 60,the edges of the laser slab 60 will increase in temperature. The pumpenergy shields 88 and 90 may be properly sized and spaced apart tomaximize efficient optical pumping of the laser slab 60. According tosome embodiments, the pump energy shields 88 and 90 serve to compensatefor manufacturing differences in pumping diode arrays.

[0058] In one preferred embodiment, the pump energy shields 88 and 90are positioned and sized to shield less than approximately 5% of thesurface area of each of the windows 86. The pump energy shields 88 and90 can comprise stainless steel tape with an acrylic-based adhesiveadhering the pump energy shields 88 and 90 to the windows 86. Inalternative embodiments, the pump energy shields 88 and 90 may compriseother materials such as ceramic or copper shielding.

[0059] While the present invention has been described with reference toone or more particular embodiments, those skilled in the art willrecognize that many changes may be made thereto without departing fromthe spirit and scope of the present invention. For example, while thediode mounts 18 have been described as having fluid flowing therein itis to be understood that diode mounts may be provided without fluidconduits and used primarily as supports for the diode array assemblies24. Each of these embodiments and obvious variations thereof iscontemplated as falling within the spirit and scope of the claimedinvention, which is set forth in the following claims.

What is claimed is:
 1. A laser gain device comprising: a laser slab forreceiving pump energy and generating an output beam, said laser slabmounted within a slab housing; at least one diode array assembly forgenerating said pump energy and emitting said pump energy from an energyemission region; at least one diode array mount for supporting said atleast one diode array assembly, said diode array mount having a firstlever portion and a second lever portion, said first and second leverportions pivoting around a fulcrum with respect to said slab housing;and an adjustment mechanism connected to at least one of said first andsecond lever portions for adjusting a pump energy angle at which saidpump energy from said energy emission region impinges on said laserslab.
 2. The laser gain device of claim 1 wherein said slab housing isstationary with respect to said at least one diode array mount and saidadjustment mechanism comprises an adjustment screw adapted to turnwithin an adjustment bracket attached to said slab housing.
 3. The lasergain device of claim 2 wherein said adjustment screw opposes a diodeadjustment support that is biased toward an end of said adjustmentscrew.
 4. The laser gain device of claim 3 wherein: said first leverportion of said diode array mount is biased toward said slab housing;said diode array assembly is mounted to said second lever portion ofsaid diode array mount; and said diode adjustment support is biased awayfrom said slab housing toward said adjustment screw.
 5. The laser gaindevice of claim 3 wherein said diode adjustment support is a pinattached to said diode array assembly.
 6. The laser gain device of claim3 wherein said diode adjustment support is adapted to move within anadjustment support slot provided in said adjustment bracket.
 7. Thelaser gain device of claim 1 further comprising one or more diodespacers placed between said fulcrum and said slab housing for adjustinga distance between said diode array assembly and said laser slab.
 8. Amethod for adjusting pump energy entering a laser slab comprising:providing a laser slab within a laser slab mount, said laser slabadapted to accept said pump energy; providing a diode array assemblyhaving an energy emission region for emitting said pump energy at anemission angle, said diode array assembly being mounted on a diode arraymount having a first lever portion and a second lever portion; biasingone of said first and second lever portions of said diode array mountwith respect to said laser slab mount; and pivoting said first leverportion and said second lever portion around a fulcrum to adjust saidemission angle of said pump energy.
 9. The method of claim 8 whereinproviding said diode assembly comprises aligning said emission regionsuch that said pump energy is directed toward said laser slab.
 10. Themethod of claim 8 wherein biasing one of said first and second leverportions of said diode array mount with respect to said laser slab mountcomprises biasing a first lever portion of said diode array mount towardsaid laser slab mount and further wherein providing said diode arrayassembly comprises mounting said diode array assembly to said secondlever portion of said diode array mount.
 11. The method of claim 8wherein pivoting said first lever portion and said second lever portioncomprises adjusting an adjustment device against which one of said firstlever portion and said second lever portion of said diode array mount isbiased.
 12. The method of claim 11 wherein adjusting an adjustmentdevice comprises turning an adjustment screw.
 13. The method of claim 8further comprising adjusting a distance between said diode arrayassembly and said laser slab by placing or removing diode spacersbetween said diode array mount and said laser slab mount.
 14. A laserslab housing comprising: first and second slab housing members defininga space therebetween for accepting laser slabs of differing dimensions,said first and second slab housing members being separated by a slabhousing dimension and each of said first and second slab housing membersbeing separated from said laser slab by respective first and second slabdistances; a laser slab within said space between said first and secondslab housing members; and one or more laser slab spacers between saidfirst and slab housing members, lengths of said laser slab spacersdefining said slab housing dimension and being replaceable with laserslab spacers having different lengths such that said slab housingdimension is alterable and at least one of said first and second slabdistances remains approximately constant for laser slabs of differingdimensions.
 15. The laser slab housing of claim 14 further comprising atleast one slab seal adapted to be compressed to a compression widthbetween one of said first and second slab housing members and said laserslab.
 16. The laser slab housing of claim 15 wherein said lengths ofsaid laser slab spacers are chosen to maintain said compression width ofsaid slab seal approximately constant when said laser slab is replacedwith a differently-sized laser slab.
 17. The laser slab housing of claim14 wherein said laser slab spacers are selected form a kit of laser slabspacers having laser slab spacers of different lengths.
 18. The laserslab housing of claim 14 wherein said one or more laser slab spacershave apertures therein for accepting assembly pins holding said firstand second slab housing members together.
 19. The laser slab housing ofclaim 14 wherein said one or more laser slab spacers are comprised ofthe same material as said slab housing members.
 20. The laser slabhousing of claim 14 wherein said laser slab is held between said firstand second slab housing members by at least one edge bar, said at leastone edge bar being adapted to accept at least one of said slab spacerstherethrough.
 21. A method for mounting laser slabs of differentdimensions comprising: providing first and second slab housing membersspaced from one another at a slab housing distance and defining aslab-receiving space therebetween; selecting from a plurality of laserslab spacers having a plurality of laser slab spacer lengths one or morelaser slab spacers to provide a desired slab housing distance; andspacing said slab housings from one another with one or more of saidlaser slab spacers.
 22. The method of claim 21 wherein adjusting saidslab housing distance comprises increasing said slab housing distancewhen laser slabs having a wider dimension are held within saidslab-receiving space and decreasing said slab housing distance whenlaser slabs having a narrow dimension are held within saidslab-receiving space.
 23. The method of claim 21 further comprisingcompressing at least one slab seal between a laser slab and at least oneof said first and second slab housing members to a compression distance.24. The method of claim 23 further comprising maintaining saidcompression distance for laser slabs having different dimensions byselecting and inserting slab spacers of appropriate slab spacer lengthsbetween said first and second slab housing members.
 25. The method ofclaim 23 further comprising mounting a laser slab in said slab-receivingspace between first and second edge bars.
 26. The method of claim 21further comprising adjusting said slab housing distance by replacingsaid laser slab spacers with laser slab spacers having different laserslab spacer lengths.
 27. The method of claim 21 further comprisingholding said first and second slab housing members together withassembly pins inserted through apertures provided within said laser slabspacers.
 28. A laser gain module comprising: a laser slab adapted toreceive pump energy and emit an output beam; a pump energy source foremitting said pump energy; gain module coolant conduits for directingcoolant in said laser gain module, said coolant cooling at least one ofsaid laser slab and said pump energy source; and a liquid-cooled heatshield adapted to receive stray radiation from at least one of saidlaser slab and said pump source, said liquid-cooled heat shieldcomprising at least one heat shield conduit accepting said coolant fromone of said gain module coolant conduits.
 29. The laser gain module ofclaim 28 wherein said at least one heat shield conduit is furtheradapted to direct said coolant toward one of said gain module coolantconduits.
 30. The laser gain module of claim 28 wherein said laser slabis mounted between first and second laser slab housing blocks, at leastone of said housing blocks having at least two cooling liquid conduitstherein, said at least one heat shield conduit accepting coolant fromone of said cooling liquid conduits of said at least one laser slabhousing block and directing coolant to another of said cooling liquidconduits of said at least one laser slab housing block.
 31. The lasergain module of claim 30 wherein said at least one housing block furthercomprises a cooling liquid diverter for directing a first portion ofsaid coolant to said heat shield and a second portion of said coolant tosaid laser slab.
 32. The laser gain module of claim 31 whereinapproximately one gallon of coolant is directed to said heat shield forevery eight gallons of coolant directed to said laser slab.
 33. Thelaser gain module of claim 28 wherein said heat shield comprises angledor curved portions to absorb stray radiation within said laser gainmodule.
 34. The laser gain module of claim 28 wherein said heat shieldcomprises a liquid-cooled heat shield base attached to one or more heatshield components adapted to absorb said stray radiation.
 35. The lasergain module of claim 28 wherein said heat shield is removable from saidlaser gain module.
 36. The laser gain module of claim 28 wherein saidcoolant is water.
 37. A method of cooling a laser gain module having acooling conduit for cooling at least one of a diode array and a laserslab and also for transmitting coolant to a heat shield having at leastone heat shield conduit therein comprising: directing coolant via saidcooling conduit to at least one of said diode array and said laser slab;receiving stray radiation from one of said diode array and said laserslab with said heat shield; and directing said coolant from said coolingconduit to said at least one heat shield conduit for the removal of heatfrom said heat shield.
 38. The method of claim 37 wherein said heatshield is removable from said laser gain module.
 39. The method of claim37 wherein said heat shield comprises a heat shield base and at leastone formed heat shield component adapted to absorb radiation and whereinreceiving stray radiation comprises receiving stray radiation at said atleast one heat shield component.
 40. The method of claim 39 wherein saidformed heat shield component comprises angled or curved surfaces forreceiving said stray radiation.
 41. The method of claim 37 furthercomprising diverting a first portion of said coolant to said laser slaband a second portion of said coolant to said heat shield.
 42. A systemfor the emission of laser light comprising: a laser slab adapted to bepumped by pump energy from at least one pump energy source; at least onewindow for accepting said pump energy, said at least one window having aslab-facing surface directed toward said laser slab; a slab coolingconduit between said laser slab and said window for passing coolant pastsaid laser slab; and at least one pump energy shield provided on saidslab-facing surface of said at least one window and adapted to prevent aportion of said pump energy exiting said slab-facing surface of saidwindow from reaching said laser slab.
 43. The system of claim 42 whereinsaid at least one pump energy shield is cooled by said coolant.
 44. Thesystem of claim 42 wherein said at least one pump energy shield isopaque.
 45. The system of claim 42 wherein said at least one pump energyshield is comprised of a material selected from the group consisting ofstainless steel, copper, and ceramic.
 46. The system of claim 45 whereinsaid coolant is water.
 47. The system of claim 42 wherein said at leastone pump energy shield is adhesively attached to said slab-facingsurface of said at least one window.
 48. A method of controlling pumpenergy entering a laser slab comprising: providing a laser slab foraccepting pump energy from a pump energy source; providing a windowbetween said laser slab and said pump energy source, said window beingseparated from said laser slab by a laser slab cooling conduit forallowing cooling liquid to cool said laser slab; and limiting a portionof said pump energy from entering said laser slab with at least one pumpenergy shield on said window between said window and said laser slab.49. The method of claim 48 wherein said at least one pump energy shieldis comprised of stainless steel and is attached to said window.
 50. Themethod of claim 49 wherein said pump energy shield is adhesivelyattached to said window.
 51. The method of claim 48 wherein said atleast one pump energy shield comprises at least a top pump energy shieldfor limiting a portion of said pump energy entering along an upper edgeof said window from entering said laser slab and a bottom pump energyshield for limiting a portion of said pump energy entering along abottom edge of said window from entering said laser slab.
 52. The methodof claim 48 wherein said at least one pump energy shield forms a pumpenergy aperture through which said pump energy enters said laser slab,said method further comprising selecting a size and shape for said pumpenergy aperture to maintain a desired pattern of isotherms within saidlaser slab.
 53. The method of claim 52 wherein selecting a size andshape for said pump energy aperture comprises selecting a size and shapeof said pump energy aperture that produces substantially verticalisotherms within said laser slab.